Process and apparatus for making variegated plastic articles



July 26, 1949.

N. o. BRODERSON ET AL 2,477,170 PROCESS AND APPARATUS FOR MAKINGVARIEGATED PLASTIC ARTICLES Filed Aug. 12, 1946 The invention will bemore particularly described with reference to the accompanying drawingin which:

Fig. 1 is a plan view of one form of an extruding machine embodying theprinciples of the invention;

Fig. 2 is an enlargedview, partly in section, of the masticating chamberand extruding head of the apparatus showing the screw in perspective;

Fig. 3 is an end view of a bridge plate;

Fig. 4 is an end view of the extruding head of the apparatus shown inFig. 2;

Figs. 5 and 6 are medial sectional and end views respectively of analternative form of extruding head; and

Fig. 7 is a cross-sectional view of a matched pair of extruded rodsproduced by the apparatus of Fig. 2.

In Fig. 1, main drivin motor I drives all the moving parts of themachine except feed screws 2 and 3 in the feed hoppers 4 and 5. Motorturns sheave 6 which drives sheave 1 through belts 8. Pinion 9, mountedon the same shaft with sheave is rotated therewith, and it meshes withthe large gear H! which drives the main shaft of the masticating andextruding device. This main shaft is connected directly with extrudingscrew II and turns the same in the direction indicated by the arrow inFig. 2. v

Counter-shaft l2, mounted in bearings I3, is rotated by the main shaftof the extruding device through sprocket chain l4 engaging suitablesprocket wheels mounted on the counter-shaft and the. main shaft of theextruding device. Counter-shaft I2, in turn, serves to drive preformpellet feeding device l5 of conventional design which feeds preformedpellets of colored or clear casein down chute l6 into the mouth ll'ofthe screw or masticating chamber I8. The driving of the preform feedingdevice is accomplished by means of sprocket chain |9 and suitablesprocket gears secured to the counter-shaft and the drive shaft of thepellet feeding device. The rate of feeding pellets to the convertingchamber may be varied by changing the ratio of the sprocket gearsassociated with sprocket chain l9.

j,The counter-shaft I2 also serves to drive adjustable cams 2n and 2|through the train including sprocket chain 22, spur gears 23 and 24 andreduction gear 25. Each of the cams 2|! and 2| has an approximatelysemicircular rise corresponding to the raised position of lever 26, andan approximately semicircular depressed surface corresponding to thelowered position of lever 26. Cam 2| is fixed to the low-speed shaft 21of the reduction gear, while cam may be angularly rotated and securedwith respect to cam 2|. By proper adjustment of the cams the lever 26may be held in raised position for from one-half to one full revolutionof shaft 21.

Lever 2G actuates a reversing switch 28 controlling feeding motor 29.When the lever 26 is in raised position, the motor runs in onedirection; when it is in lowered position'the motor runs in the oppositedirection; and when the lever is in intermediate position the motor doesnot operate.

f Motor 29 drives feed screws 2 and 3 through the train includin belt'30, which rotates the high speed shaft 3| of reduction gear32, bevelgears 33, and 34, mounted on the low-speed shaft of the reduction gear,and bevel gears and 36 operatively engaging bevel gears 33 and 34, re-

4 spectively. Feed screws 2 and 3 are of the same hand but rotate inopposite directions simultaneously, so that while one is feedingmaterial from its hopper the other is tending to withdraw material fromaround the discharge opening of its hoppen; Upon reversal of the motor,there is a slight delay between the time when material ceases to be fedfrom one hopper and begins to be fed from the other due to the timerequired for the material which has been backed up in the latter hopperto reach the discharge opening 45 thereof. There is a still furthershort hiatus or dwell occasioned by the reversing switch 28 passingthrough its'neutral position causing the motor to stop. This dwellbetween alternations is important, as will be explained hereinafter, inconnection with the process phase of the invention.

By adjusting cams 20 and 2| and by choosing between hoppers 4 and ;5,any desired ratio of two granular materials may be fed to the extrudingmachine. The ratio of materials fed thus may be varied independently ofthe over-all time rate of feed, since the overa.ll time rate of feed is'dependent primarily upon the speed of the re'ductiongear 32.

The frequency of alternation of feeding the material may be varied bychanging spur gears 23 and 24 to give the desired speed to cams 20 and2|. Likewise, this change may be effected independently of the over-alltime rate of feed.

The over-all time rate of feed may be varied by changing the speed ofmotor 29, as by employing a rheostat, 'not shown, in the power line tothe motor. Or the rate of feed may be determined by the relative size ofsheaves 3'1 and 38.

Referring to Fig. 2, 18 represents the screw or masticating chamber ofthe machine. The walls 39 of the chamber are provided with coolingjackets 40. Bridge'plate 4|, an enlarged end view of which is shown inFig. 3, forms the discharge end of the screw chamber. Orifice 42 isconcentric with the axis of screw The orifice has a considerably smallerdiameter than the end 43 of screw Bridge plate 4| cooperates with theend 43 of the screw to provide a constricted centrally convergingpassage 44. The general shape of this chamber may be varied somewhatfrom the cylindrical shape as shown to some other convenient form.

Converting head 46 is provided with heat control jacket 41. Theconverting chamber 48 here has the form of a truncated cone with itsminor base surmounted by a cylinder. A function of this chamber is toprovide a space ,of decreasing cross section in the direction of flow ofthe material being worked whereby the body of material as a whole issomewhat elongated in its passage therethrough. At the small end of theconverting chamber'there is located agasket or washer 49.

Collar 50 is screwed onto the converting head at its discharge end andreceives the washer 49 and the extruding nozzle 5|. The collar isjacketed at 52'. The nozzle shown in Fig. 2 is provided with twoorifices, and appears in end view in Fig. 4. The nozzle illustrated inFigs. 5 and 6 may be substituted for that shown in Fig. 2.

In describing ithe exemplary operation of the apparatus for theproduction of variegated rods of two colors, the description of thefunction of thepellet feeding device I 5 will be deferred, since thefeeding of pellets is an optional procedure. A granular plasticsubstance capable of being extruded is chargedinto the hoppers 2 and 3.The

color of the substance in each of the hoppers is different. For example,casein colored black with suitable dye. or pigment may be placed inhcpper' 7: and white. or clear'casein maybe placeck in'hopper 3'. The:cam is. set. with-respecttoz cam ZI: so that the proportion. of whiteand black desired in the resulting. productisfed alternately from therespective hoppers. The frequency of feed" alternations. is adjusted byselecting the proper'gear ratio between gears. 23 and Z4 to give thedesired grain structure-in the-resultant prod-'- uct. hereinbefore,so-that the machine will'zaccept altthe'material fed without: allowingthis material toback up into the mouth li-T of the screw chains her ortoproceed so far down the chamberthat poor consolidation and masticationis effected. The feeding of such extrusion apparatusrequiresthesupervision of arr-operator who may make slight adjustments-in theover-all feed-rate as. occasion demands order to maintain theproperamount of material in-the screw chamber.

With both the main driving motor land the feeding motor 29 running,alternate portions of white and black casein are transferred'frorfithehoppers 2 and- 3 into the mastiCati-rig chamber- IB' Between successiveadditions ofportions of" caseinthere is a short dwell-,- and this shortspace of time permits'on'e portion of granular caseirl to advancesufficiently far forward that it will not become excessively m-ixed withthe succeeding portionbefore it is compacted.

successive portions of difieren-tlycolored plastics are masticat'edinchamber l=8--and forced into a continuously advancing strea-m'of"masticated material} The successive portions form a series ofvarieolered sections transversely of the stream which in the advance ofthe stream, because of the greater'retard'ation'of the peripheralportions thereof, are drawn outlong-itudinally into conical sectionshaving their apices-substantially centrally located. in the stream, asshown in Fig. 2. By splitting the stream' diametrically and separatelyextruding the diametrically op posed portions of the stream byme'ans ofextriidi ingnozzlesof the. type showna't: S ll in Fig; 2=a 'nd in Figs;5- and. 6, the. extruded portions are given a gi'aiined appearance.simulating: natural-- horn, shell: and. the like. The transversesection'scof the are. shown in Fig. Land-it Will be under stoodthat:buttons may be madefrdm the rods-b y machining and cuttintransverse slices therefrom which have the desired thickness andthereafter drilling thread holes as may be necessary. Great savings inmaterial are thus realized, since a minimum of waste material is removedin making each button.

The above description does not take into account supplementing thedecorative effect produced by the addition of preformed pellets ofcasein, and this procedure will now be discussed.

The pellet feeding device I5 is of conventional design, and is operatedby the main driving motor as described. Its function is to introduce atpredetermined intervals a pellet of plastic substance into the screwchamber. When working with casein in the main hoppers, the pellets maybe small cylinders molded from previously masticated and extrudedcasein.

The color of the added pellets may be the same as the color of thedarker portion of granular casein fed from one of the hoppers 4 and 5.The pellets may also have the color of the lighter colored casein or maybe of any other suitable color depending upon the color combinationdesired in the finished buttons. The use of these pellets adds extremelydistinct and somewhat The over-all feed rate-is set; explainedit. isdesirablethat: thexcolor shall not bleed from.

the darker intothe' lighter portions of casein;- We have found that biyproperly adjusting the moisture content of. the two caseins such. bleedinga is minimized or' entirely overcome. It is;

'- usual to adjustrthe moisture'content of casein'ta be extruded to avalue approximating 18 to 20% to permit 'eas'y working of the materialin the"extrud-ing machine; To prevent. bleeding, wei pr'efer t'oincr'eas'e' the moisture content of the light e'r fraction of casein oneor two percent, and iii any event less than 1 0%, and to decrease themoisture" content of the colored fraction by an amount such thatthe-total moisture content or the extruded rod" isapproximately thatrequired for best extruding conditions. A strict balance cf n-ioisturecontentis not an essential require: ment in securing sharp separation ofcolors." The moisture content" of the colored casein may: be more-orless than that necessary to'bal'a'nce" the average-moistureanalysis ofthe-extruded ro'd so-lon'g as good working conditionsarema ni-" tained.It will be seen. that this feature providesa moisture differentialbetween'the two fractions of casein such that the flow of moisturebetween thefractionsis. in a direction from the lighter or uncoloredcasein to the. darker or colored casein. This now tends toiretairrthecoloring substance: in the colored fraction and I practically eliminatesbleeding-of coolor irito the lighter fraction.

When colored pellets are used they preferably" havea lower moistureanalysis than they other fractions of casein to prevent bleeding.

Althoughthe apparatus and: the method of" extruding grained rodis:applicable to all ex trudable plasti'c'substance's, it has beendescribed'- principally with reference to casein. Wehave discovered thata more distinct mottling is ob-' tained ifithe m'asses of granulatedcasein which are-alternately fed to the machine have previousl'ybeenworked as by'extruding or otherwise subjecting the casein toheat; pressure and elongation, andsubsequently grinding to produce:granulated casein; If this previously worked casein. is recite theapparatus o'f'this invention,

- a more clear-cut and distinct-pattern is obtained in the extruded rod.

This application is a continuation-in-part of our copending applicationSerial No. 309,490, filed December 15, 1939, for Variegated plasticarticles which has become abandoned.

We claim:

1. The process of making variegated articles which comprises masticatingsuccessive discontinuous portions of differently colored plasticmaterial, forcing said masticated portions into a continuously advancingstream comprising successive different colored portions extendingtransversely across substantially the entire stream, splittin saidadvancing stream substantially along the longitudinal axis thereof intoa plurality of portions, and extruding said portions into separatearticles.

2. The process of making variegated articles which comprises masticatingsuccessive discontinuous portions of differently colored plasticmaterial, forcing said masticated portions into a continuously advancingstream comprising successive different colored portions extendingtransversely across substantially the entire stream, splitting saidadvancing stream substan- 1. tially'alongthelongitudinal axis thereofinto two portions, and extruding said portions into sep-' arate rods. vg

- 3. Apparatus for making variegated extruded articles which comprisesmeans defining a longitudinally extended conduit for the advancement ofa stream of plastic material, means for introducing into said conduit asuccession of different colored portions of plastic material extendingsubstantially transversely and substantially en-v tirely across saidconduit, means for forcing said plastic material along said conduit,means for splitting the advancing stream of plastic materialsubstantially along its longitudinal axis into a plurality of portions,andmeans for extruding said portions into separate articles.

4. Apparatus for making variegated extruded articles which comprisesmeans defining a longitudinally extended conduit for the advancement ofa stream of plastic material, means for introducing into said conduit asuccession of different colored portions of plastic material extendingsubstantially transversely and substantially entirely across'saidconduit, means for forcing said plastic material along said conduit,means for splitting the advancing stream of plastic materialsubstantially along its longitudinal axis into two portions, and meansfor extruding said portions into separate rods.

5. Apparatus for making variegated extruded articles which comprisesmeans providing a cylindrical masticating chamber, a masticating screwrotatably'mounted within said chamber, said screw having a relativelyblunt front end, the front end of said masticating chamber conforming tothe front end of said screw and being spaced therefrom to provide arestricted, centrally converging passage, means for supplying successivediscontinuous portions of differently colored plastic material to saidmasticating chamber, means defining an elongated conduit for theadvancement of a stream of plastic material, centrally disposedrestricted outlet means at the front end of said chamber opening intoone end of said conduit, means positioned near the other end of saidconduit for splitting a stream of plastic material advancingtherethrough substantially along its longitudinal axis into a pluralityof portions, and means for extruding said portions into separatearticles.

6."App'aratus for making variegated extruded articles which comprisesmeans providing a cylindrical masticating chamber, a masticating screwrotatably mounted within said chamber, said screw having .a relativelyblunt front end, the front end of said masticating chamber conformingto'the front end of said screw and being spaced therefrom to provide arestricted, centrally converging passage, means for supplying successivediscontinuous portions of differently colored plastic material to saidmasticating chamber, means defining an elongated conduit for theadvancement of a stream of plastic material, centrally disposedrestricted outlet means at the front end of said chamber opening intoone end of said conduit, means positioned near the other end of saidconduit for splitting a stream of plastic material advancingtherethrough substantially along its longitudinal axis into twoportions, and means for extruding said portions into separate rods.

7. The process of making buttons which comprises masticating successivediscontinuous portions of diii'erently colored plastic material, forcingsaid masticated portions into a continuously advancing stream comprisingsuccessive difierent colored portions extending transversely acrosssubstantially the entire stream, splitting said advancing streamsubstantially along the longitudinal axis thereof into two portions,extruding each of said portions into a separate cylindrical rod, andcutting buttons from said rods transversely thereof.

NEIL O. BRODERSON. EDWIN C. BRODERSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

